The invention relates to an osteosynthetical fixing element for the fixing of a bone implant which bone bore-hole and an expanding body which can be driven into an opening of the accommodating body and where the accommodating body is radially expandable by a wedge effect.
EP-B1 409 364 discloses a connecting element for osteosynthesis which is designed as an expandable, elastically deformable sleeve. The sleeve has a diameter which, reduces from an end side and is provided with a slot extending in the longitudinal direction. The expansion of the sleeve is effected by a pin which is designed so as to be axially symmetrical and preferably tapers in conical fashion in the direction of insertion and whose outer diameter is greater than the smallest outer diameter of the sleeve and smaller than the greatest outer diameter thereon. At the periphery of the sleeve different kinds of toothing elements are provided consisting for example of sawtooth-shaped barbs, helical or concentric projections.
Upon the driving-in of the pin, the outer wall of the sleeve, inserted into a corresponding bore in the bone fragments to be connected, is pressed against the surrounding bone material and wedged accordingly.
A disadvantage of the known implant for the osteosynthetic connection of reset bone fragments consists, in particular, in that--independently of the quality of its stabilising effect--primarily the attainable stability of the connection is unpredictable and highly variable in the longitudinal direction.
Furthermore, upon the fixing of this element torsion stresses arise which are unpredictable in terms of their effects and which reduce the stability of the connection.